Studies were made of 100 con-secutive children, examined electroencephalographically within four weeks after a head injury, according to the type of electroencephalographic abnormality and the severity of the cerebral insult. The following conclusions were drawn There is excellent correlation between the degree of injury and abnormality in the electroencephalogram. However, striking abnormalities may result from negligible injury. The most common electroencephalographic abnormality seen, particularly between ages 4 and 11, is posterior slowing. Serial study is necessary for the proper evaluation of the abnormalities. Sleep-state recording in follow-up electroencephalograms, in which spike discharges and asymmetries may be picked up that otherwise would be missed, is important.